No, the computer right now is basically telling it for X amount of air entering the engine, inject Y amount of fuel to create a certain A:F ratio. The O2 sensor lets it know where the mixture is.

The thing about it is that at WOT (Wide Open Throttle) the engine goes into what is known as Open Loop mode. This is because the O2 sensors that come on cars are really only accurate close to the 14.7:1 ratio. As it gets further away from that number, it becomes exponentially more inaccurate. This is why a good tuner uses a wide-band O2 sensor. Anyway,when this happens, the ECU stops taking readings from the O2 sensor and basically injects a pre-determined amount of fuel. Engineers from the factory tend to play it safe and tell it to inject more than what is needed. You don't want to run lean at WOT. It would take more than a CAI to cause it to run 12.5:1. A tune is definitely in order.

The DI motor does have a high static CR, but you got to remember that it's making those numbers on 87 octane. The DI bit pushes the normal CR boundaries quite a bit, even under turbo applications.

Static CR itself isn't the problem, it's the ability to fine tune that defines how well a forced induction system runs. Lowering the CR gives you more of a safe-zone for screw ups vs. running right on the edge of a FI+high CR situation. Hell, I've seen some 12:1 CR port injection motors w/ full turbos put out insane numbers and still be well within limits -- it's all in the tune. One major advantage (as I see it) is the hardware already present from a computer standpoint...the Motec ME9. This little bastard is capable of a super high degree of monitoring and correction, especially compared with older technologies. It's like Atari vs. Xbox360 man, crazy stuff. That was the biggest problem w/ DI up until the last few years -- having an ECU with enough power to control the system, and still be commercially cost effective.

From a mechanical standpoint, the V6 bottom end is forged, pistons are aluminum w/ heat coating to deal with the stress of DI. They also have factory oil squirters ...

Now, if they'd only come out with the 7.2L V12 engine... that would be a hellova lot of fun to tune.

The DI motor does have a high static CR, but you got to remember that it's making those numbers on 87 octane. The DI bit pushes the normal CR boundaries quite a bit, even under turbo applications.

Static CR itself isn't the problem, it's the ability to fine tune that defines how well a forced induction system runs. Lowering the CR gives you more of a safe-zone for screw ups vs. running right on the edge of a FI+high CR situation. Hell, I've seen some 12:1 CR port injection motors w/ full turbos put out insane numbers and still be well within limits -- it's all in the tune. One major advantage (as I see it) is the hardware already present from a computer standpoint...the Motec ME9. This little bastard is capable of a super high degree of monitoring and correction, especially compared with older technologies. It's like Atari vs. Xbox360 man, crazy stuff. That was the biggest problem w/ DI up until the last few years -- having an ECU with enough power to control the system, and still be commercially cost effective.

From a mechanical standpoint, the V6 bottom end is forged, pistons are aluminum w/ heat coating to deal with the stress of DI. They also have factory oil squirters ...

Now, if they'd only come out with the 7.2L V12 engine... that would be a hellova lot of fun to tune.

This.

With out overextending too much the DI means that you're not taking air and fuel on the intake stroke. It's just air. So carbs are like air/fuel mixing centers port injection is shooting atomized fuel with the air and compressing it all on the compression stroke.

Fuel is a liquid and can't be compressed as much as air. So with direct injection. You have nothing but air being compressed and as the air is compressed you have all that pressure in the chamber and THEN the fuel is injected and ignited.

Compression needs to be payed attention to, but it's not as important on carb or port injection methods. Which is why you can run such a high compression. It's all air being compressed. The only thing you really need to worry about is can the internals handle all the energy happening in the combustion chamber.

Got a link for a stock cobra to see the differences or at least what RPM the abruptness started? Also a GTP I'd be curious at seeing the differences in A:F. If it's jus a measure to keep it from leaning out at the top end and cause detonation.

The reason I ask is because if it's running this rich it might not be a complete burn of the fuel. So residual fuel would be accumulating to a point.

Got a link for a stock cobra to see the differences or at least what RPM the abruptness started? Also a GTP I'd be curious at seeing the differences in A:F. If it's jus a measure to keep it from leaning out at the top end and cause detonation.

The CTS tested higher with the same engine. I wonder why?
Baseline run: vehicle produced 263.0 rwhp and 241.7 lbs/tq.
With a CAI and corsa exhaust(no other tuning) it tested
294.2 rwhp and 261.3 lbs/tq

The CTS tested higher with the same engine. I wonder why?
Baseline run: vehicle produced 263.0 rwhp and 241.7 lbs/tq.
With a CAI and corsa exhaust(no other tuning) it tested
294.2 rwhp and 261.3 lbs/tq